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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2] x86: generic MSRs save/restore
Jan Beulich wrote:
> This patch introduces a generic MSRs save/restore mechanism, so that
> in the future new MSRs save/restore could be added w/ smaller change
> than the full blown addition of a new save/restore type.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>
>
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -1127,10 +1127,117 @@ static int hvm_load_cpu_xsave_states(str
> return 0;
> }
>
> -/* We need variable length data chunk for xsave area, hence
> customized
> - * declaration other than HVM_REGISTER_SAVE_RESTORE.
> +#define HVM_CPU_MSR_SIZE(cnt) offsetof(struct hvm_msr, msr[cnt])
> +static unsigned int __read_mostly msr_count_max;
> +
> +static int hvm_save_cpu_msrs(struct domain *d, hvm_domain_context_t
> *h) +{
> + struct vcpu *v;
> +
> + for_each_vcpu ( d, v )
> + {
> + struct hvm_msr *ctxt;
> + unsigned int i;
> +
> + if ( _hvm_init_entry(h, CPU_MSR_CODE, v->vcpu_id,
> + HVM_CPU_MSR_SIZE(msr_count_max)) )
> + return 1;
> + ctxt = (struct hvm_msr *)&h->data[h->cur];
> + ctxt->count = 0;
> +
> + if ( hvm_funcs.save_msr )
> + hvm_funcs.save_msr(v, ctxt);
> +
> + for ( i = 0; i < ctxt->count; ++i )
> + ctxt->msr[i]._rsvd = 0;
> +
> + if ( ctxt->count )
> + h->cur += HVM_CPU_MSR_SIZE(ctxt->count);
> + else
> + h->cur -= sizeof(struct hvm_save_descriptor);
> + }
> +
> + return 0;
> +}
> +
> +static int hvm_load_cpu_msrs(struct domain *d, hvm_domain_context_t
> *h) +{
> + unsigned int i, vcpuid = hvm_load_instance(h);
> + struct vcpu *v;
> + const struct hvm_save_descriptor *desc;
> + struct hvm_msr *ctxt;
> + int err = 0;
> +
> + if ( vcpuid >= d->max_vcpus || (v = d->vcpu[vcpuid]) == NULL )
> + {
> + dprintk(XENLOG_G_ERR, "HVM restore: dom%d has no vcpu%u\n",
> + d->domain_id, vcpuid);
> + return -EINVAL;
> + }
> +
> + /* Customized checking for entry since our entry is of variable
> length */ + desc = (struct hvm_save_descriptor *)&h->data[h->cur];
> + if ( sizeof (*desc) > h->size - h->cur)
> + {
> + printk(XENLOG_G_WARNING
> + "HVM%d.%d restore: not enough data left to read MSR
> descriptor\n", + d->domain_id, vcpuid);
> + return -ENODATA;
> + }
> + if ( desc->length + sizeof (*desc) > h->size - h->cur)
> + {
> + printk(XENLOG_G_WARNING
> + "HVM%d.%d restore: not enough data left to read %u
> MSR bytes\n", + d->domain_id, vcpuid, desc->length);
> + return -ENODATA;
> + }
> + if ( desc->length < HVM_CPU_MSR_SIZE(1) )
> + {
> + printk(XENLOG_G_WARNING
> + "HVM%d.%d restore mismatch: MSR length %u < %zu\n",
> + d->domain_id, vcpuid, desc->length,
> HVM_CPU_MSR_SIZE(1)); + return -EINVAL;
> + }
> +
> + h->cur += sizeof(*desc);
> + ctxt = (struct hvm_msr *)&h->data[h->cur];
> + h->cur += desc->length;
> +
> + if ( desc->length != HVM_CPU_MSR_SIZE(ctxt->count) )
> + {
> + printk(XENLOG_G_WARNING
> + "HVM%d.%d restore mismatch: MSR length %u != %zu\n",
> + d->domain_id, vcpuid, desc->length,
> + HVM_CPU_MSR_SIZE(ctxt->count));
> + return -EOPNOTSUPP;
> + }
> +
> + for ( i = 0; i < ctxt->count; ++i )
> + if ( ctxt->msr[i]._rsvd )
> + return -EOPNOTSUPP;
> + /* Checking finished */
> +
> + if ( hvm_funcs.load_msr )
> + err = hvm_funcs.load_msr(v, ctxt);
> +
> + for ( i = 0; !err && i < ctxt->count; ++i )
> + {
> + switch ( ctxt->msr[i].index )
> + {
> + default:
> + if ( !ctxt->msr[i]._rsvd )
> + err = -ENXIO;
> + break;
> + }
> + }
> +
> + return err;
> +}
> +
> +/* We need variable length data chunks for XSAVE area and MSRs, hence
> + * a custom declaration rather than HVM_REGISTER_SAVE_RESTORE.
> */
> -static int __init __hvm_register_CPU_XSAVE_save_and_restore(void)
> +static int __init hvm_register_CPU_save_and_restore(void)
> {
> hvm_register_savevm(CPU_XSAVE_CODE,
> "CPU_XSAVE",
> @@ -1139,9 +1246,22 @@ static int __init __hvm_register_CPU_XSA
> HVM_CPU_XSAVE_SIZE(xfeature_mask) +
> sizeof(struct hvm_save_descriptor),
> HVMSR_PER_VCPU);
> +
> + if ( hvm_funcs.init_msr )
> + msr_count_max += hvm_funcs.init_msr();
> +
> + if ( msr_count_max )
> + hvm_register_savevm(CPU_MSR_CODE,
> + "CPU_MSR",
> + hvm_save_cpu_msrs,
> + hvm_load_cpu_msrs,
> + HVM_CPU_MSR_SIZE(msr_count_max) +
> + sizeof(struct hvm_save_descriptor),
> + HVMSR_PER_VCPU);
> +
> return 0;
> }
> -__initcall(__hvm_register_CPU_XSAVE_save_and_restore);
> +__initcall(hvm_register_CPU_save_and_restore);
>
> int hvm_vcpu_initialise(struct vcpu *v)
> {
> --- a/xen/include/asm-x86/hvm/hvm.h
> +++ b/xen/include/asm-x86/hvm/hvm.h
> @@ -109,6 +109,10 @@ struct hvm_function_table {
> void (*save_cpu_ctxt)(struct vcpu *v, struct hvm_hw_cpu *ctxt);
> int (*load_cpu_ctxt)(struct vcpu *v, struct hvm_hw_cpu *ctxt);
>
> + unsigned int (*init_msr)(void);
> + void (*save_msr)(struct vcpu *, struct hvm_msr *);
> + int (*load_msr)(struct vcpu *, struct hvm_msr *);
> +
> /* Examine specifics of the guest state. */
> unsigned int (*get_interrupt_shadow)(struct vcpu *v);
> void (*set_interrupt_shadow)(struct vcpu *v, unsigned int
> intr_shadow); --- a/xen/include/public/arch-x86/hvm/save.h
> +++ b/xen/include/public/arch-x86/hvm/save.h
> @@ -592,9 +592,21 @@ struct hvm_tsc_adjust {
>
> DECLARE_HVM_SAVE_TYPE(TSC_ADJUST, 19, struct hvm_tsc_adjust);
>
> +
> +struct hvm_msr {
> + uint32_t count;
> + struct hvm_one_msr {
> + uint32_t index;
> + uint32_t _rsvd;
> + uint64_t val;
> + } msr[1 /* variable size */];
> +};
> +
> +#define CPU_MSR_CODE 20
> +
> /*
> * Largest type-code in use
> */
> -#define HVM_SAVE_CODE_MAX 19
> +#define HVM_SAVE_CODE_MAX 20
>
> #endif /* __XEN_PUBLIC_HVM_SAVE_X86_H__ */
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